doc: add RafaelGSS as last security release stewards

Signed-off-by: RafaelGSS <rafael.nunu@hotmail.com>
PR-URL: #64843
Refs: nodejs-private/security-release#74
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Aviv Keller <me@aviv.sh>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Ruy Adorno <ruy@vlt.sh>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>

Author: RafaelGSS

doc/contributing/security-release-process.md

@@ -41,6 +41,7 @@ The current security stewards are documented in the main Node.js
 | HeroDevs and NodeSource | Marco / Rafael  | 2026-Jan-13  |
 | NodeSource              | Rafael          | 2026-Mar-24  |
 | Platformatic            | Antoine         | 2026-Jun-18  |
+| NodeSource              | Rafael          | 2026-Jul-29  |
 | Datadog                 | Bryan           |              |
 | IBM                     | Joe             |              |
 | Platformatic            | Matteo          |              |